On Tue, Jun 29, 2010 at 02:33:55PM +0300, Boaz Harrosh wrote:
>
> If a callback is retried at nfsd4_cb_recall_done() do to
> some error. The returned rpc reply would then crash here:
>
> @@ -514,6 +514,7 @@ decode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_cb_sequence *res,
> u32 dummy;
> __be32 *p;
>
> + BUG_ON(!res);
> if (res->cbs_minorversion == 0)
> return 0;
Thanks, applied. There may be a delay before it shows up in my
for-2.6.36 queue, while I sort out a few other bugs.
(We still have problems here: getting a new slot isn't always the
correct thing to do, depending on the error. But this seems an
improvement....).
--b.
>
> [BUG_ON added for demonstration]
>
> This is because the nfsd4_cb_done_sequence() has NULLed out
> the task->tk_msg.rpc_resp pointer.
>
> Also eventually the rpc would use the new slot without making
> sure it is free by calling nfsd41_cb_setup_sequence().
>
> This problem was introduced by a 4.1 protocol addition patch:
> [0421b5c5] nfsd41: Backchannel: Implement cb_recall over NFSv4.1
>
> Which was overlooking the possibility of an RPC callback retries.
> For not-4.1 case redoing the _prepare is harmless.
>
> Signed-off-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
> ---
> fs/nfsd/nfs4callback.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> index f3b5015..3bbeae8 100644
> --- a/fs/nfsd/nfs4callback.c
> +++ b/fs/nfsd/nfs4callback.c
> @@ -913,7 +913,7 @@ static void nfsd4_cb_recall_done(struct rpc_task *task, void *calldata)
> if (dp->dl_retries--) {
> rpc_delay(task, 2*HZ);
> task->tk_status = 0;
> - rpc_restart_call(task);
> + rpc_restart_call_prepare(task);
> return;
> } else {
> atomic_set(&clp->cl_cb_set, 0);
> --
> 1.6.6.1
>
>
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